Chrysler Repair: blower motor, blower motor resistor, infinite ohms

Question
my blower motor in my 91 caravan suddenly stopped working i checked the fuse its ok should i just go ahead and replace it or is there something else i should check first

Answer
Hi Darcy,
Before buying a new motor unit I would verify that it isn't working. Begin by finding the disconnect for the motor, under the dash near the motor. It has 2 wires: a dark green from the fuse should, when you disconnect it and check with a voltmeter, show that it has 12 volts on it coming from the fuse when the ignition switch is on; and a black/tan wire which should be grounded (read 0 ohms resistance when measured from it to a shiney metal surface of the body nearby) when the fan motor it turned to run on high speed.
If both those check out then the supply and return wires and items through which the current must pass are o.k.
But just to be sure you could try jumping the 12V that you measure on the dark green to the motor side of the connector and use a second jumper to ground the tan/black wire on the motor side of the connector and in that way test the motor proper. The reason I would urge you to test this is that there is the blower motor resistor block and the speed switch that could be at fault rather than the motor and those are in the circuit of the tan/black wire on the way to a ground point. In fact, if you measure the resistance of the tan/black to ground with the motor speeds set on different setting the resistance reading should rise from 0 (high) to increasing values of ohms until you reach 'off' where it should read infinite ohms compared to a ground point. That way you will check out the resistor block and the control switch in its entirety. If all these tests "pass' and you can't get the blower to run with the 2 jumpers, then go for a replacement motor at a wrecking yard or the dealer as you choose.
Roland